Noble-metal alloy.



GEORGE H. DUFOUR, 013

OAK PARK, ILLINOIS, ASSIGNOR TO MARSHALL FIELD 6.,

COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

NOBLE-METAL ALLOY.

No Drawing.

To all whom it may concern:

Be it known that I, GEORGE H. DUFOUR, a citizen of the United States, residing at Oak Park, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Noble-Metal Alloys, of which the following is a specification.

This invention relates to an alloy of metals, and has for its object to produce a composite metal having definite and permanent characteristics that render it suitable for use in the manufacture of jewelry and other articles for the production of which noble metals or precious metals are generally employed. More particularly, the object is to produce a metal that will have those inherent qualities which render the metal platinum, desirable for the purposes above mentioned, such, for instance, as high ductility and malleability which facilitate working the metal into any desired form of stock materials or any special shape and design of article to be produced; attractive appearance due to natural color, and reception of polish or special finish; physical and chemical properties which adapt itto resist abrasion and ordinary acids or other oxidizing influences, and consequent capacity for retaining its appearance; and, withal, the intrinsic value of the material itself which lends definite worth to the article regardless of its other charateristics.

The new alloy is composed of three metals, each a noble metal in itself, namely, gold, palladium, and platinum, with the firstnamed commercially plentiful metal largely in excess, and with the rarer metals in comparatively small proportions, though sufiicient in quantity to definitely change the appearance of the gold to that of platinum, and lend the necessary hardness to the compound.

I have discovered by experiment that if palladium, which is a silver-white metallic element resembling platinum, be alloyed with gold in the proportion of about 6 pwt. of palladium to 20 pwt. of gold 24 carat fine, an alloy is produced which is white in color, although soft physically, and that if about 1 pwt. of platinum is includedin this alloy it imparts to the alloy the hardness of about 5% iridio platinum, while retaining an appearance closely resembling that of platinum. as well as all other characteristics of platinum which make it desirable for use in Specification of Letters Patent.

blocks or pieces Patented Oct. 22, 1918.

Application filed April 15, 1918. Serial No. 228,551.

the production of jewelry or other articles for wh ch noble metals or precious metals are ordlnarily employed. The proporations above named are only approximate, the invention not being limited to exact proportlons.

The gold, which is a commercially plentiful element, is largely in excess. The palladium, which, while comparatively rare, is commercially not so scarce as platinum, is only in suflicient quantity to produce the whitening influence upon the gold, and the platinum, which is now exceedingly scarce commercially, is in the smallest proportion, being only sufiicient to lend hardness to the alloy, and being of a character that improves rather than detracts from the color sought to be obtained. In general terms, the gold may be said to be about 74%, the palladium about 213 70, and the platinum about 44 of the alloy.

An exact formula which I have employed, andfound to be very satisfactory in practice, consists of 20% pwt. of 24 carat gold, 6 pwt. of palladium, and 1% pwt. of platinum. These metals are preferably alloyed by first melting the palladium and platinum together, rolling the resultant mixture 0 metals into a sheet, reducing this compound metal to sub-divided form, as by cutting the sheet into blocks, mixing it with the gold in similarly sub-divided form, melting together the gold and the compound of palladium and platinum, rolling the resultant complex metal into a sheet, cutting this sheet into and mixing the same, again melting the complex metal to render the alloy homogeneous, and then manipulating the final alloy into such physical form or forms as may be desired or most useful.

As is well known, the fusing point of platinum is very high, being about 3227 F. Hence, some source of ver high heat must be employed in the several melting steps, such, for instance, as the electric arc furnace or oxyhydrogen blow pipe flame,- preferably the latter.

The new alloy above described fully realizes all of the objects hereinbefore mentioned. and is found to be particularly desirable as a substitute for platinum in mounting diamonds and other gems, since it has substantially the same appearance or artist c qualities as platinum, and equivalent chemical and physical qualities, in that it does not tarnish and is exceedingly durable. Its specific gravity (beiiig about 17.7) is considerably less than that of platinum, or even gold, and the degree of hardness is greets? than that of gold, which is its largest constituent.

Eclsim:

1. An alloy for use in making articles of jewelry, having appearance iez'manently simulating that of platinum, and composed of gold, palladium and platinum, with he proportion of gold about three times out of the palladium and "platinum and the proportion of the palladium about five times that of the platinum.

2. An alloy composed of gold, palladium and platinum, in the proportions of about .7 2% gold, 21-}75 palladium, and4'1% platimum.

Signed at Chicago, State of Illinois, this 20 12th day 01* April, A. o. 1918.

GEGRGE DUFUUR.

Witnesses:

MAURIQE V. H PUCKEY, FRANK F, IVIZLLER. 

